One of the causes of snoring and apnea is that the pillow is too high when sleeping on the back.
You can try it yourself. Please lie on your back and try to breathe with your mouth closed. If you have difficulty breathing, it means that your pillow is high.
Normal pillows are often taller (or the same height) in the middle than on both sides, so they are too high to breathe easily when a person lie in a supine position in the middle of the pillow.
In other words, if you set the height of the middle of the pillow to an appropriate height, there is a high possibility that snoring and apnea will disappear.
Recommended pillows are Nishikawa, My pillow, Smile pillow. The center is lower than both sides.